It was the second such attack in Volgograd in two months. In October a woman identified as Naida Asiyalova detonated a vest of explosives aboard a bus in the city, killing herself and six others.
In that case, the authorities linked her by marriage to an explosives expert working with an Islamic rebel group in Dagestan, the southern republic where the police have struggle to suppress an insurgency by Muslim separatists. A month later the authorities announced that they had killed her husband and four others in a raid in the region.
The republics of the North Caucasus, including Dagestan, Chechnya and Adygea, have for nearly two decades been embroiled in complex, ever-shifting armed conflicts that the International Crisis Group recently called “the most violent in Europe today.”
The violence has left hundreds dead already this year and prompted the authorities to make extraordinary efforts to keep it from reaching Sochi, the Black Sea resort city that will be the host of the Winter Olympic Games six weeks from now.
Doku Umarov, the Chechen rebel fighter who now leads a terrorist group known as the Caucasus Emirate, vowed in July to target Sochi explicitly, calling the Games “satanic.” “They plan to hold the Olympics on the bones of our ancestors, on the bones of many, many dead Muslims, buried on the territory of our land on the Black Sea,” Mr. Umarov said in a video statement.